Different weaver species usually nest separately, but two species sometimes occupy a tree. Seldom are there three species, but that rare combination turned the fever tree at Andersson’s Lodge into a bustling colony of weaver nests in January 2020. The good rains that fell early in January got male Red-billed Buffalo and Masked Weavers busy building nests, and then Chestnut Weavers arrived, adding a third species, and more colour and commotion. Males of all three weavers busied themselves for much of the day, collecting nesting material, chasing neighbouring boys and displaying their prowess to any passing lady weavers.
Weavers seem to invest in breeding at two levels in these semi-arid environments where rain falls sporadically. The first is nest building by males, a testing phase during which the birds can see if the rains continue and new supplies of food materialise from the flush of new, lush vegetation. This first, more tentative stage is the preserve of males in most weavers, and so only males are present building, at least until conditions are seemingly right for females to start laying eggs. Females also use this phase to assess the qualities of males in the colony, with the result that the fittest chaps end up having several wives, each in her own nest.
Egg laying signals the beginning of the second investment. This is a substantial, relatively long commitment. Not only is the energetic cost of egg production high, but laying and incubating eggs and then rearing chicks means that the adults are tied to that nesting event, that nest tree and that immediate environment for at least the next six weeks until the chicks fledge.Gone then is the chance to explore other areas where better rains might have fallen, or to find healthier mates, for example. It is time to stay, and get the job done! This is the way weavers count, and even re-count their metaphorical eggs before they hatch.